What’s the news on sucralose?

These past days the press has been abuzz with frightening tales:

• This Common Artificial Sweetener Can Break Down DNA, Scientists Warn
• Sucralose Damages DNA, Linked to Leaky Gut
• Chemical found in common sweetener damages DNA
• Chemical found in widely used sweetener breaks up DNA
• Chemical from Splenda breaks up DNA

How true and/or serious is this?

Firstly, let’s manage expectations. Pineapple juice also breaks down DNA, but is not generally considered a health risk. So let’s keep that in mind, while we look into the science.

Is sucralose as scary as pineapple juice, or is it something actually dangerous?

The new study (that sparked off these headlines)

The much-referenced study is publicly available to read in full—here it is:

Toxicological and pharmacokinetic properties of sucralose-6-acetate and its parent sucralose: in vitro screening assays

You may notice that this doesn’t have quite the snappy punchiness of some of the headlines, but let’s break this down, if you’ll pardon the turn of phrase:

• Toxicological: pertaining to whether or not it has toxic qualities
• Pharmacokinetic: the science of asking, of chemicals in bodies, “where did it come from; where did it go; what could it do there; what can we know?”
• Sucralose-6-acetate: an impurity that can be found in sucralose. For perspective, the study found that the sucralose in Splenda contained “up to” 0.67% sucralose-6-acetate.
• Sucralose: a modified form of sucrose, that makes it hundreds of times sweeter, and non-caloric because the body cannot break it down so it’s treated as a dietary fiber and just passes through
• In vitro: things are happening in petri dishes, not in animals (human or otherwise), which would be called “in vivo”
• Screening assays: “we set up a very closed-parameters chemical test, to see what happens when we add this to this” ⇽ oversimplification, but this is the basic format of a screening assay

Great, now we understand the title, but what about the study?

Researchers looked primarily at the effects of sucralose-6-acetate and sucralose (together and separately) on epithelial cells (these are very simple cells that are easy to study; conveniently, they are also most of what makes up our intestinal walls). For this, they used a fancy way of replicating human intestinal walls, that’s actually quite fascinating but beyond the scope of today’s newsletter. Suffice it to say: it’s quite good, and/but has its limitations too. They also looked at some in vivo rat studies.

What they found was…

Based on samples from the rat feces (somehow this didn’t make it into the headlines), it appears that sucralose may be acetylated in the intestines. What that means is that we, if we are like the rats (definitely not a given, but a reasonable hypothesis), might convert up to 10% of sucralose into sucralose-6-acetate inside us. Iff we do, the next part of the findings become more serious.

Based on the in vitro simulations, both sucralose and sucralose-6-acetate reduced intestinal barrier integrity at least a little, but sucralose-6-acetate was the kicker when it came to most of the effects—at least, so we (reasonably!) suppose.

Basically, there’s a lot of supposition going on here but the suppositions are reasonable. That’s how science works; there’s usually little we can know for sure from a single study; it’s when more studies roll in that we start to get a more complete picture.

What was sucralose-6-acetate found to do? It increased the expression of genes associated with inflammation, oxidative stress, and cancer (granted those three things generally go together). So that’s a “this probably has this end result” supposition.

More concretely, and which most of the headlines latched onto, it was found (in vitro) to induce cytogenic damage, specifically, of the clastogenic variety (produces DNA strand breaks—so this is different than pineapple’s bromelain and DNA-helicase’s relatively harmless unzipping of genes).

The dose makes the poison

So, how much is too much and is that 0.67% something to worry about?

• Remembering the rat study, it may be more like 10% once our intestines have done their thing. Iff we’re like rats.
• But, even if it’s only 0.67%, this will still be above the “threshold of toxicological concern for genotoxicity”, of 0.15µg/person/day.
• On the other hand, the fact that these were in vitro studies is a serious limitation.
• Sometimes something is very dangerous in vitro, because it’s being put directly onto cells, whereas in vivo we may have mechanisms for dealing with that.

We won’t know for sure until we get in vivo studies in human subjects, and that may not happen any time soon, if ever, depending on the technical limitations and ethical considerations that sometimes preclude doing certain studies in humans.

Bottom line:

• The headlines are written to be scary, but aren’t wrong; their claims are fundamentally true
• What that means for us as actual humans may not be the same, however; we don’t know yet
• For now, it is probably reasonable to avoid sucralose just in case